Referring to FIG. 2a, there is shown a conventional, remotely controlled lock system for use with an automotive door lock mechanism. This system permits the driver to either lock or unlock the associated door by operating a portable transmitter (not shown) without the need to operate the mechanical door key cylinder KS of the door lock mechanism. More specifically, the door lock mechanism is further equipped with locking and unlocking solenoids. The transmitter held by the driver transmits electromagnetic waves including information on a certain key code. The waves are received by the transmitter installed on the vehicle, and the key code is detected and compared with a code previously stored in a memory. If they coincide, then the locking or unlocking solenoid is energized to actuate the door lock mechanism, for locking or unlocking the door. Thus, when the driver or other person gets in the vehicle, he or she operates the transmitter to transmit a signal for unlocking the door. When he or she gets out of the vehicle, the operator operates the transmitter to send out a signal for locking the door. In this way, the door can be locked and unlocked without the need of mechanical operation.
A vehicular door lock mechanism of this kind has a second latch position to secure safety during movement of the vehicle. When the door is in this second latch position, it is incompletely closed. Pushing the door beyond the latch position will bring the door into a primary latch position, where the door is completely closed. However, when the door is in the second latch position and the door is locked, pushing the door beyond the second latch position will unlock the door. Door lock systems of this type often receive instructions for locking the door from relatively remote locations. Therefore, there is the possibility that the driver locks the door without knowing that it is incompletely closed and then another person pushes the door beyond the second latch position to thereby unlock the door, creating the danger of theft of the vehicle.
The conventional door lock system has another problem. Specifically, if the driver erroneously operates the transmitter and leaves the vehicle without noticing that the door has been unlocked, then the door is left unlocked, creating the danger of theft of the vehicle.